It is known how to manufacture, by unit production means, cylindrical or prismatic hollow bodies of synthetic resin reinforced with fibres; in the processes followed in such manufacture a mould is coated with successive layers of synthetic resin and fibres, the mould being removed after the synthetic resin is polymerised. In some cases the mould can be used to produce a new unit, depending on whether the mould is destroyed when the pattern is removed from it.
With the apparatus and the process according to the present invention, the hollow cylindrical or prismatic body manufactured is displaced, moving constantly over the mould, thereby avoiding the inconveniences inherent to removal of the pattern from the mould unit by unit. Also in accordance with this invention, the polymerisation of the obtained cylindrical or prismatic body begins practically when the wall thereof attains the predetermined thickness.
The process according to the invention is characterised by the operations of: placing a fibrous substructure previously impregnated with synthetic resin on a long mandrell which rotates continuously; moving the said fibrous substructure, by continuous traction, along the geometric axis of said mandrell; continuously rolling or winding around the substructure thus formed, other fibrous elements of like nature which have been previously impregnated with the same or another synthetic resin, said elements overlapping and/or superimposing one another to form a layer of the desired thickness; compressing the outer surface of said layer to eliminate possible hidden air bubbles; gauging and correcting where necessary the dimensions of the hollow body being manufactured; treating said hollow body to achieve polymerisation, curing and hardening of the resin, and cutting the continuous hollow body thus obtained into predetermined lengths.
The process of this invention is further characterised in that said fibrous substructure, which circumferentially can totally or partially cover the outer surface of the chuck, can be constituted by elements of a continuous nature such as yarn, fabric, gauze, etc.
Another object of this invention is an apparatus suitable for putting into practice the manufacturing method just described, which apparatus consists essentially of a mechanically driven rotary disc which can rotate in one direction or another at variable speed, provided on at least one of its sides with means for feeding fibrous elements of continuous nature to a long mandrel forming a part with said disc and placed centrally with respect thereto, its geometric axis being perpendicular to the plane of the cited disc, the periphery of the latter being provided with a plurality of guide means designed to conduct said continuous fibrous elements from their means of supply, so that when the disc rotates they can submerge in a tank containing a synthetic resin, said tank being located directly beneath the disc, the mandrel having a cross-sectional shape according to the cross-sectional shape of the end product desired; means for feeding other continuous fibrous elements, previously impregnated with synthetic resin, to the said rotary mandrel in a zone in which the mandrel is already covered by said fibrous substructure, the purpose of these means being to roll or wind said other continuous fibrous elements, with superimposition or overlapping, to achieve a layer of predetermined thickness on the mentioned fibrous substructure; means fo exerting a compressing force on the outer surface of the hollow body being manufactured to thus eliminate hidden air bubbles as the said body advances over the cited chuck; means for gauging the dimensions of the hollow body as it advances during manufacture and still remains on said mandrel; means for achieving the polymerisation, curing and hardening of the resin; means for subjecting the forward end of said fibrous substructure first realised on the mandrel to traction, to start the displacement of the substructure along the length of the mandrel, said means of traction being applied continuously during manufacture and with light pressure upon the outer surface of the finished hollow body to automatically keep it moving along the length of the cited mandrel, and finally cutting means to function at predetermined moments to thus obtain predesignated lengths of the finished continuous hollow body.
These and other objects of the present invention are explained more particularly in the following detailed description.